The Effect of Neighboring Grain Orientation on Dislocation-Grain Interaction in Ti-5553 Alloy

Abstract

The misorientation angle of grain boundaries (GBs) is invalid to evaluate the interaction of dislocations/twins with GBs, because the misorientation relation between two neighboring grains is determined by the misorientation angle/axis pair of the corresponding GBs. In this paper, the mechanisms associated with the interaction between GBs and <111> dislocations are investigated in Ti-5553 alloy with body-centered cubic structure. Slip traces transmitted into the neighboring grain or blocked by GBs are observed on the surface of the sample via secondary electron imaging. The corresponding slip system is determined with the combined use of EBSD-detected grain orientation. The experimental results indicate that most slips can transfer at low angle GBs, while some slips can also transmit at high angle GBs. Crystallographic alignment-based analysis shows that slip transfer happens at GBs with favorable parameters of high geometric alignment ( [[EQUATION]] ) and low residual Burgers vector ( [[EQUATION]] ). The general relation of GB misorientation angle with [[EQUATION]] and [[EQUATION]] is investigated. Low angle GBs always possess high [[EQUATION]] and low [[EQUATION]] , which contributes to their preference of slip transfer. However, only some high angle GBs meet the requirement of decent alignment parameters. Finally, the orientations of best neighboring grains that are favorable for slip transfer are pointed out. The results are useful for optimizing neighboring grain condition to design metals with excellent deformation compatibility at GBs.

Keywords: Slip transfer, Grain boundary, Misorientation, EBSD, titanium alloy